other vertebrata (i.e., birds, reptiles, amphibia, and fishes), in having--
(a) Hair.
(b) A diaphragm.
(c) Only one aortic arch, and that on the left side of the body.
(d) Its young born alive. (But two very reptile-like mammals of
Australia, the duck-billed platypus and the echidna, lay eggs, and
certain fish and reptiles bear living young.)
(e) Epiphyses to its vertebral -centre- [centra].*
(f) The cerebral hemispheres covering the mid-brain.
(g) Corpora quadrigemina instead of bigemina.
[(h) A corpus callosum.]
[(i) A spirally coiled cochlea to the internal ear.]
[(In respect to h and i also, the echidna and platypus are scarcely
mammalinan.)]
* But certain mammals have no such epiphyses.